Method for the manufacture of mercury dispenser devices to be used in fluorescent lamps

Abstract

An improved method is described for the manufacture of mercury dispenser devices to be used in fluorescent lamps, of the type wherein the dispenser material ( 2 ) is contained inside a metal tube ( 1 ), these dispensers providing a more uniform distribution of mercury, with lower fluctuations from one device to the other. This is obtained by a method according to which a tubular metal container ( 1 ′) having a larger diameter than the final one ( 1 ), after the filling thereof with said dispenser material ( 2 ) is passed between at least two pairs of rollers ( 3, 3′, 4, 4 ′) whose axes of rotation are parallel to each other and perpendicular to the advancing direction (X-X′) of the tubular container ( 1 ), until a reduction of the cross-section of the latter to the desired value is obtained, and is finally cut to the right size into the single dispenser elements

What is claimed is:  
     
       1. A method for the manufacture of mercury dispenser elements to be used for fluorescent lamps, with metal envelope containing a composition ( 2 ) suitable for releasing mercury, comprising the steps of: 
       a) filling with said composition ( 2 ) a tubular metal envelope ( 1 ′) having a diameter larger than that required for the single final mercury dispensers;  
       b) passing said tubular envelope ( 1 ′) between at least two pairs ( 3 ,  3 ′;  4 ,  4 ′) of opposed rollers, having the axes perpendicular to the advancing direction (X-X′) of the tubular envelope ( 1 ′) for a number of rolling passes sufficient for obtaining a filiform section ( 1 ) having the desired transversal size; and  
       c) cutting said section ( 1 ) into single pieces of about 0.2-1 cm which form the finished dispensers.  
     
     
       2. A method according to  claim 1 , wherein at each rolling pass the cross-section of the envelope is reduced of about 12%. 
     
     
       3. A method according to  claim 1  or  2 , wherein the material of said envelope ( 1 ,  1 ′) is a ductile metal, having a good electrical conductivity, releasing no gases under heating and forming no amalgam with mercury. 
     
     
       4. A method according to  claim 3 , wherein said metal is nickel and the initial thickness of the tubular envelope ( 1 ′) is between 0,1 and 0,75 mm. 
     
     
       5. A method according to  claim 3 , wherein said metal is nickel and the initial diameter of the tubular envelope ( 1 ′) is between 3 and 15 mm. 
     
     
       6. A method according to  claim 1 , wherein said composition ( 2 ) is formed of a mixture of mercury dispensing material with a mercury release promoter material. 
     
     
       7. A method according to  claim 1 , wherein said composition ( 2 ) is formed of a mixture of a mercury dispensing material with a getter material. 
     
     
       8. A method according to  claim 6  or  7 , wherein said mixture is introduced into the tubular envelope ( 1 ′) in the form of a powder having particle size not higher than 125 μm. 
     
     
       9. A method according to  claim 1 , wherein at each rolling the axis of rotation of the roller pair is varied by an angle of (360/n)′ with respect to the preceding rolling, wherein n is the total number of rollings.